config.sub: correct Bull DPX/2-[123]00 and DPX/20 canonical names.

config.sub was mapping all single-component shorthands matching the
shell glob `dpx2*` to ‘m68k-bull-sysv3’, which is incorrect.  Of the
four different machines once manufactured by Groupe Bull whose model
number can be abbreviated ‘dpx2something’, only two were m68k-based:
the DPX/2-200 and DPX/2-300.  The DPX/2-100, on the other hand, had an
i386 CPU.  And the DPX/20 was a completely different beast, released
years later and based on the POWER architecture.

I’ve chosen to keep making ‘dpx2’ map to ‘m68k-bull-sysv3’ as the
DPX/2-200 and /2-300 seem to have been the most widely used.  config.sub
now understands ‘dpx2100’, ‘dpx2200’, and ‘dpx2300’ as shorthands for
‘i386-bull-sysv3’, ‘m68k-bull-sysv3’, and ‘m68k-bull-sysv3’ respectively.
It also accepts ‘dpx21xx’, ‘dpx22xx’, and ‘dpx22xx’ as equivalent to
these, but no other variations; in particular, ‘dpx2xxx’, which was in
the test suite, no longer works, as it is ambiguous.

(As far as I can tell, there weren’t actually any submodels of any of
these systems, so I could be persuaded to remove the …xx aliases.
I kept them mainly because of the test suite formerly testing dpx2xxx.)

Finally ‘dpx20’ now maps to ‘rs6000-bull-bosx’.  Both the ‘rs6000’ and
‘bosx’ components of this name are debatable, but I *think* it is what
config.guess would do on this machine.

Sources for Bull DPX/2whatever history:

 - https://oldskool.silicium.org/stations/bull_dpx20.htm
 - https://www.feb-patrimoine.com/english/bull_dpx2.htm
 - https://www.feb-patrimoine.com/english/unix_and_bull.htm

Note in particular “Que cette machine soit estampillée BULL ou IBM,
elle faisait tourner AIX (l'Unix d'IBM)” on the first of these pages,
which is why I say “bosx” is debatable…

Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>

doc/config.sub.1

@@ -1,5 +1,5 @@
 .\" DO NOT MODIFY THIS FILE!  It was generated by help2man 1.48.5.
-.TH CONFIG.SUB "1" "March 2024" "GNU config.sub (2024-03-12)" "User Commands"
+.TH CONFIG.SUB "1" "May 2024" "GNU config.sub (2024-05-27)" "User Commands"
 .SH NAME
 config.sub \- validate and canonicalize a configuration triplet
 .SH SYNOPSIS